Steam boiler



Oct. 11,. 1932.

E. E. NOBLE 1,881,879

STEAM BOILER Filed Nov. 21. 1928 INVEN TOR W ATTORNEYS Patented Oct. 11,1932 UNITED STATES ERNEST EDWARD NOBLE, or EULWELL, sUNEEELANn, ENeLANnAssIGNoE 'ro BABGOGK & wILcox COMPANY, OF BAYONNE, NEW

J ERSEY ATENT. oFFIcE STEAM BOILER Application filed November 21, 1928,Serial No. 320,838, and in Great Britain December 12, 1927;

This invention relates to improvements in water-tube boilers and moreparticularly to improvements in water-tube boilers of the Stirling orsemi-vertical bent tube type.

It is known that steam bubbles ascending through'water in a tube producea movement of the water in the "direction in which they travel, and thatthe most efficient path promoting the greatest velocity of the water isa directly verticalpath. It is known also that steam'bubbles formedin ahorizontal tube will remain at rest in the upper part of the tube,producing no movement of the water or circulating effect in the tube.

In tubes therefore which lie close to the horizontal the circulationwill be slow and in tubes which lie close to the vertical thecirculation rapid.

It is an object of the present invention to provide an a rangement ofthe bank of tubes nearest the furnace of a Stirling or like type ofboiler by which the maximum amount of heating surface is obtained insuch bank and the maximum amount of such heating surface is exposed tothe radiant heat of the combustion chamber. 7

To this end, in accordance with the invention the tubes or some of thetubes of the front bank of a Stirling or similar bent tube type ofboiler are bent intermediate to their terminal bends so that one portionof each such tube of such bank occupies a semi-horizontal positionandthe other portion of each such tube occupies a semi-vertical position.Preferably, one portion of each such tube lies substantiallyhorizontally over the furnace producing a relatively weak circulationbut affording the absorption of the maximum amount of radiant heat,while the other part of such tube is relatively vertical, the therelatively vertical portion being of sulficient length to augment thecirculation or induce the circulation in the relatively hori-' zontalpart of the tubes to the desired acceleration. may be above or below thesemi-horizontal part of the tube. In the latter case, the high velocitycirculating portion of the tube impels the slower circulation to greatervelocity.

The semi-vertical part of the tube Generally, the ends of the tubesofboilers of the type referred to are bent'toenter the drums radially andthe tubes of the bank nearest the furnace will thusordinarily have threebends in their lengthbut one only when the drums are so arranged that"the axis of each straight part of the tube will pass through the centreof the drums into -which they were expanded, or two bends when the axisof one leg of the tube passes through a drum centre. The tube bend of;

the present invention -is one purposely formed for the purpose describedof pro-- ducing a more active circulation in a tube which wouldotherwisetend to be steamcongested tion. r I

JERSEY, A. CORPORATION OF .NEW

owing to relatively slow circula The invention is illustrated in theaccornpanying drawinginwhich the figure is a longitudinal section of aStirling boiler with the tubes of the bank nearest the furnace.

constituted in accordance with this invention, the semi-horizontal partof such tubes being located beneath the s'ub stantially'vertical part ofthe tubes.

Referring to the figure, 10 and 11 indicate I p thesteam and Water drumsand 12 the mud drum. The two steam and Water drumslO and 11 areconnected by a bank of tubes 13,

and the steam and water drum 11 is connected to the mud drum 12 byspaced banks of tubes 14-1 and 1&2, between which is disposed atransverse superheater indicated generally at 15. In the embodiment ofmy invention illustrated in the figure, thetubes of the bank 142 locatednearest the furnace are bent' at l6 intermediate the usual terminalbends so that each tube is provided with a portionl? which is morenearly horizontal than vertical of considerable extent over the furnacewhere itreceives the 1nax1mum amount of radlant heat, and avertical ornearly vertical portion 18 serving to induce or increase a circulationin the portion 17 in which the circulation tends to be sluggish.Preferably watercooling tubes 27 extend. downwardly from the drum 12-adjacent to the front walls 28 to a header 29. Similarly. water coolingtubes 30 extend downwardly from the drum 11 to a" header 31, the headers29 and 31 being con:

nected bya row of horizontally extending tubes 32 which support thefloor 33. The

tubes 27, 32 and provide a circulation separate from the boilercirculation. The tubes 27 are preferably located in a duct 34, to whichair may be supplied from the space 35 beneath the floor of the furnacechamber, and the amount of which maybe regulated by a damper 36.Openings 37 are preferably provided in the flooro-f the furnace, throughwhich air may pass into the combustion ehambemthe amount of which isregulated by dampers 38. Air may be introduced into the space 35 bymeans of doors 39.- Auxiliarycirculation,

' howeventogetherwith the openings in the a heater 15, the tubes ofthe'upper bank 141 tubes 100, which connect the upper drum 10 a and aredirected downwardly bya ba -lile 1 11 extending from the lower drum 12along the upper sideof the bank of tubes 141, and are then directed overthe bank of tubes 13 and to the lower drum 12 to an outlet flue 101.

- Iclaim: n 1. In ajlow head bent tube boiler and its 7 furnace, anupper 'drum, a lower drum, a first bank of tubes freely exposedthroughout practically all of their lengths to radiant heat from thefurnace and bent indifferent degreesattheir ends so that they enter bothdrums radially, the tubes being bent intermediate their terminal bendsto provide horizontally inclined sections extending from the lower drumtransversely of the furnace to upright tubesections located betweenvertical planes bounding the upper drum and extendlngto the upper bentends to utilizea culation in the more nearly horizontal portion of thetube, and asuperheater located in the space between the two portions ofsaid bank.

3. In a steam boiler and its furnace, an up-' per and a lower drum, abank of tubes conmeeting said drums, said bank being divided into anupper group and a lower group with a space betweenthe two, said lowergroup having a'less number ,of'rows of tubes than the upper group, eachtube'of thelower group being bent intermediate its ends to form oneportion that is morenearly horizontal than vertical and formingthefmajorfortion of the length of the tube and locate above the furnacechamber, another portionloca-ted at the upper end that is'morenearlyvertical than horizontal, the more nearly vertical por-' tionbeing of suflicient length to induce or increase the circulation in themore'nearly horizontal portion of the tube, anda superheater located inthe space'between the twov portions of said bank, all of the'gases from.said furnace flowing across said boiler and" superheater tubes;

density differential which induces in the a horizontally inclinedsections a flow sufiicient to prevent excessive heat damage, a super-[heater locatedimmediately above the horizontally inclined tubesections, and a second bank of tubes joining the drums and shieldedfromradiant'heat from the furnace only by the first bank of tubes andthe superheater.

2. In a steam boiler and its furnace, an upper and a lower drum, a bankof tubes conmeeting said drums, saidbank being divided into an uppergroup'and a lower group with a space betweenthe two, said lower groupERNEST EDWARD NOBLEQ:

having a fewer number of rowsof tubes than a r the upper group, eachtube of the lower group a being bentintermediate its ends to form oneportion that'is more nearly horizontal'than vertical and formingthema'jor portion, of

r the length of the tube and located'above the I furnace,;and anotheradjacent portion that is more nearly vertical than horizontal, the morenearly vertical portion being of sufficient length'to induce. orincrease thecire

